Uterine contraction sensing system and method

ABSTRACT

The present invention provides a system for enabling the sensing of changes in pressure in response to uterine muscle tone changes relating to contractions, and for enabling the evaluation of contractions based thereon. The system enables a portion thereof to effectively and efficiently project at least partially below the non-compressed abdominal surface, and provides electrical isolation of the system elements. It enables ease of use and enhanced patient comfort. It also enables maximized sensitivity and minimized system loading retention pressure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 11/123,862 filedMay 6, 2005 now U.S. Pat. No. 7,862,521, which was acontinuation-in-part of a co-pending application Ser. No. 10/113,890filed on Mar. 27, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is generally related to devices for sensing uterinecontractions during labor, and more particularly, to a system and methodfor sensing the frequency and duration of contractions, and forestimating the relative intensity thereof.

2. General Background and State of the Art

During a contraction, the muscle tone of the uterus increases. Thisincrease in muscle tone applies pressure to the abdomen. The abdomenhardens and the shape changes due in part to the muscles surrounding theanterior ligament of the uterus pulling the abdomen forward.

It is known to provide systems for estimating the force of uterinecontractions during labor, generally known as tocodynamometers, whichsense, in relative terms, the increase and decrease in abdominalpressure relating to uterine contractions, and enable evaluationthereof. Such systems have typically included a cantilevered beam as asensor, and a button as a force collector, which is connected to thesensor by a link pin. The output from the system is sent to a. fetalmonitor, which displays the relative pressure in the form of a digitalreading and strip chart recording. The clinician, in reviewing the chartrecording, can observe the progress of labor in terms of contractionfrequency and duration, and can obtain a rough indication of therelative intensity of the contractions.

However, such systems are relatively large and bulky, require relativelylarge devices to hold them in place, and are expensive. Further, theyare relatively difficult to use, require relativly high belt tensionwhich is uncomfortable, and tend to migrate and require repositioning.

It would therefore be desirable to provide a sensing system which wouldsense the frequency and duration of uterine contractions during labor,and estimate the relative intensity thereof, in a manner which wouldmaximize the sensitivity of the system and enhance ease of use andpatient comfort. It would further be desirable to enable uniqueleveraging thereof, for loading onto the abdomen with the exertion ofsubstantially minimal retention pressure. It would still further bedesirable to enable support of the system so as to project into theabdomen wall to efficiently reside below the non-compressed abdominalsurface. Moreover, it would be desirable to provide electrical isolationof the patient, to prevent the flow of current thereto

Therefore, there has been identified a continuing need to provide asensing system which will effectively sense uterine contractionfrequency and duration during labor, for enabling efficient estimationof the relative intensity thereof.

INVENTION SUMMARY

Briefly, and in general terms, the present invention, in a preferredembodiment, by way of example, is directed to a system for sensing thefrequency and duration, of uterine contractions during labor andestimating the relative intensity thereof. The system is able to sensechanges in pressure in response to uterine muscle tone changes relatingto contractions, and to enable a fetal monitor to be connected theretofor evaluation of contractions. The system includes a pressure sensor,for sensing changes in pressure responsive to uterine muscle tonechanges, positionable against the exterior abdominal wall proximate theuterine muscle, connectable to a fetal monitor for evaluation ofcontractions during labor, and supportable so as to project into theabdominal wall to reside at least partially below the noncompressedsurface of the abdomen. The system also includes a supporting element,for supporting the pressure sensor such that the pressure sensorprojects into the abdominal wall to reside at least partially below thenon-compressed surface of the abdomen.

In accordance with another aspect of the invention, the supportingelement may include extending portions which extend from the opposedsides thereof, which include attachment portions and attachment pointsat the opposed ends thereof, for enabling a securing element to beconnected to the attachment portions and attachment points in theopposed ends of the extending portions, to secure the system about theabdomen. The system further includes a force collector, which includesedges thereof. The leveraging provided by the extending portionsincluding the attachment portions, and a leveraging ratio of thedistance from the attachment points through the force collector edges,is sufficiently flexible to enable deflection with the tension exertedby the securing element thereon, so that the supporting element conformsto the natural curvature of the abdomen.

In another aspect of the invention, the force collector is secured tothe pressure sensor, and a protective cover extends over the forcecollector for protectively covering the force collector. The protectivecover may have a vent hole therein, for enabling the venting of trappedair therethrough, and for preventing zero shifts which might occur dueto thermal effects. The protective cover enables the force collector toslide over the patient's skin, and prevents sticking upon repositioningthereof, which might otherwise cause negative pressure readings when thepressure cover is unloaded and returns to its natural state.

In still another aspect of the invention, the force collector includesan outer section and an inner section, and the coefficient of thermalexpansion of the outer section of the force collector is substantiallysimilar to the coefficient of thermal expansion of the inner section ofthe force collector, to prevent a zero shift in the pressure reading asthe system warms on the patient's skin.

In a further aspect of the invention, the force collector furtherincludes an outer portion of the outer section, and an inner portion ofthe outer section, and the average thickness of the outer portion of theouter section of the force collector is less than the average thicknessof the inner portion of the outer section of the force collector, toovercome slight differences in coefficients of thermal expansion of theouter portion and the inner portion of the outer section of the forcecollector. The outer portion of the outer section is retained firmlyagainst a non-moving surface, keeping the thickness of the outer portiondown in this area, and allowing the outer section to move more freelyover the inner portion of the outer section, so as to negate at least aportion of any expansion differences.

In still further aspects of the invention, the supporting memberincludes a plurality of contact pads, and the system further includes acable for connecting to a fetal monitor at one end thereof, a pluralityof connectors extending from the opposite end of the cable and securedto the plurality of contact pads, and a plurality of wires extendingfrom the sensing member to the contact pads. The plurality of connectorsmay each comprise solid unstranded telephone cable, and the cable whichis connectable to the fetal monitor may include an extended ventinglumen for enabling venting therethrough, and for enabling underwater usethereof. Solid wire makes it less labor intensive to solder to thecontact pads, as there is no twisting and trimming of strands.

In accordance with other aspects of the invention, the plurality ofconnectors in the cable which is connectable to the fetal monitor areable to be soldered directly to the contact pads, for providing a secureconnection thereof. In still further aspects of the invention, theprogramming element comprises a user interface module, includes aprocessor, and is programmable for a time within the period of theminimum time required to complete a flush of the toilet to the maximumtime required to drain all of the water from a toilet tank. It ispositionable at a user-accessible location.

In other aspects of the invention, the opposed ends of the extendingportions of the supporting element include slots and posts, and thesecuring element includes opposed ends and has buttonholes. The opposedends of the securing element are able to extend directly over the post,and each of the buttonholes is able to stretch over and interlock withthe post to engage therewith for securing the system about the abdomen.

In another aspect of the invention, the opposed ends of the extendingportions of the supporting element include slots, and the securingelement includes opposed ends, each of which includes interengageableelements. The opposed ends of the securing element are able to extendthrough the slots in the opposed ends of the extending portions and foldthereover, and the interengageable elements are able to interengage forsecuring thereof.

In still other aspects of the invention, the system further includes acover, for covering the supporting member, the sensing member, and aportion of the cable which is connectable to the fetal monitor. Thecover includes a pair of posts, one on each of the opposed ends thereof,the securing element includes opposed ends, and has buttonholes, andeach of the buttonholes in the securing element is able to stretch overand interlock with one of the posts to engage therewith for securing thesystem about the abdomen.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded top perspective view of a sensing system inaccordance with aspects of the present invention;

FIG. 2 is a bottom perspective view of a sensing member, wires, andcontacts in a supporting member;

FIG. 3 is a bottom partly fragmentary plan view of the sensing system;

FIG. 4 is a top plan view of a pressure sensor and a supporting elementin the sensing system;

FIG. 5 is an elevational partly sectional view of a pressure sensor, aforce collector, and a supporting element in the sensing system;

FIG. 6 is an elevational cross-sectional view of a pressure sensor and aforce collector in the sensing system; FIG. 6 is an undersideperspective view of a converting element in the present invention;

FIG. 7 is an elevational partly fragmentary view of the system includinga ridge area in the supporting element;

FIG. 8 is an elevational partly fragmentary view of the system includinga counterbore area in the supporting element;

FIG. 9 is an elevational view of a supporting element and a securingelement in accordance with aspects of the present invention; and

FIG. 10 is a perspective view of a cover for the supporting element anda securing element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, in which like reference numerals refer tolike or corresponding parts, the system according to the inventionsenses the frequency and duration of uterine contractions during laborand estimates the relative intensity thereof. The system is able tosense changes in pressure in response to uterine muscle tone changesrelating to contractions, and to enable a fetal monitor to be connectedthereto for evaluation of contractions.

FIG. 1 presents a sensing system 10 in accordance with the invention,which enables the sensing and monitoring of uterine contractions. Thesensing system 10 according to the invention includes a pressure sensor12, for sensing changes in pressure responsive to uterine muscle tonechanges. The pressure sensor 12 is positionable against the exteriorabdominal wall proximate the uterine muscle, and is connectable to afetal monitor for evaluation of contractions during labor. It issupportable so as to project into the abdominal wall to reside at leastpartially below the non-compressed surface of the abdomen. The system 10further includes a supporting element 14, for supporting the pressuresensor 12, such that the pressure sensor 12 projects into the abdominalwall to reside at least partially below the non-compressed surface ofthe abdomen. Also, the system includes a force collector 16, secured tothe pressure sensor 12 so as to bear against the exterior abdominal wallproximate the uterine muscle. The force collector 16 projects into theabdominal wall to reside at least partially below the non-compressedsurface of the abdomen. The force collector 16 moves responsive touterine muscle tone changes, as by displacing or compressing so as toexert pressure responsive thereto relative to the pressure sensor 12.Further, as seen in FIG. 3, the system includes a securing element 18,for enabling the securing of the pressure sensor 12, the supportingelement 14, and the force collector 16 in position against the exteriorabdominal wall proximate the uterine muscle.

The pressure sensor 12 is generally small and lightweight, and thesupporting element 14 is generally low profile and lightweight. Thepressure sensor 12 is further able to be actuated by an excitationvoltage from a fetal monitor, and to send a signal voltage back to thefetal monitor responsive to changes in pressure. The pressure sensor 12may comprise a piezo-resistive pressure sensor. It includes a supportingmember 20, and a sensing member 22 for sensing changes in pressureresponsive to uterine muscle changes relating to contractions, and forenabling a fetal monitor to be connected thereto. The sensing member 22is supported in the supporting member 20.

There is shown in FIG. 6 a cross-sectional view of the supporting member20 which is able to be formed as a supporting part, and which isextendable between the pressure sensor 12 and the supporting element 14.The supporting member 20 may for example include a gel cup 24 whichincludes a wall portion 26, and a base portion 28. The gel cup 24 iscomprised of generally molded plastic material, and is able to be filledwith a non-conductive silicone gel to form a portion of the forcecollector 16. The supporting member 20 further includes a bondingelement 30, for bonding the force collector 16 to the gel cup 24, and aceramic chip substrate 32. The supporting member 20 may alternativelyfor example comprise a gel, cup 24, comprised of generally moldedplastic material, and a ceramic chip substrate 32, or for example maycomprise a ceramic chip substrate 32.

Referring to FIG. 2, the supporting member 20 includes a plurality ofcontact pads 34. A plurality of wires 36 connect the sensing member 22to the contact pads 34. In the event of the application of a voltage orcurrent exceeding a limit, the wires 36 connecting the sensing member 22to the contact pads 34 will fail substantially instantaneously,preventing current from flowing to the patient. The contact pads 34further are able to receive a plurality of connectors 38, as seen inFIG. 1, which extend in a cable 40 for a fetal monitor. Some babydeliveries are performed in water, requiring a system which iswaterproof, as it may be submerged. The sensing member 22 is referencedto atmospheric pressure for proper pressure measurement, whereby forsuch deliveries a vent is required, which is provided though the cable40. The plurality of connectors 38 in the cable 40 may each comprisesolid strand telephone cable, and the cable 40 may include an extrudedventing lumen 42 for enabling venting therethrough, and for enablingunderwater use thereof. The plurality of connectors 38 in the cable 40may be soldered directly to the contacts pads 34 in the sensing element12, for providing a secure connection thereto. The system 10 alsoincludes a cover 44, for covering the supp supporting member 20, thesensing member 22, and a portion of the fetal monitor cable 40.

The sensing member 22 is supported in the supporting member 20 such thatthe sensing member 22 is able to project into the abdominal wall toreside at least partially below the non-compressed surface of theabdomen. The sensing member 22 comprises the active area of the pressuresensor 1.2. It includes resistors, which may comprise for example thinfilm resistors deposited thereon, which resistors are able to change theresistance with. changes in applied pressure. The resistors in thesensing member 22 may comprise a balanced resistor network, which maycomprise a silicon semiconductor Wheatstone bridge. The sensing member22 and the supporting member 20 for example may comprise a pressuretransducer. Alternatively for example the sensing member 22 and asupporting portion of the supporting element 20 may comprise a pressuretransducer, or for example the sensing member 22 and a supporting partof the supporting element 20 may comprise a pressure transducer. Theceramic chip substrate 32 of the supporting member 20 may includecompensating resistors therein, for providing compensation for theresistors in the sensing member 22.

As further illustrated in FIG. 6, the force collector 16, which is ableto interact with the sensing member 22 by displacing or compressing soas to exert pressure on the sensing member 22 responsive to uterinemuscle tone change, is supported in the supporting member 20. The forcecollector 16 is formed of a material which is able to be dispensed andformed relative to the gel cup 24. The gel cup 24 includes the bondingelement 30 for providing an adhering portion, to enable the material ofwhich the force collector 16 is formed to adhere thereto. The forcecollector 16 includes an outer section 46, an inner section 48, and aninterface 50 (FIG. 1) between the outer section 46 and the inner section48. The supporting member 20 supports the sensing member 22 and theinner section 48 of the force collector 16 therein, and supports theouter section 46 of the force collector 16 thereon. The outer section46, which may be comprised for example of an ultraviolet-cured flexibleadhesive, projects from the supporting element 14. The inner section. 48is comprised of compliant material, for example a silicone gel, andcontacts the sensing member 22. The force collector 16 projects from thesupporting element 14 and is moveable therein. The supporting member 20and the inner section. 48 of the force collector 16 are further able tosupport the pressure sensor 12 so as to isolate the pressure sensor 12from the external environment, to prevent current from flowing to thepatient. The compliant material of the inner section 48 of the forcecollector 16 is able to be formed in the wall portion 26, on the baseportion 28 of the gel cup 24 and the ceramic chip substrate 32, and overand about the piezo-resistive pressure sensor 12.

The force collector 16 is generally in the shape of a nipple, and may becomprised of a generally soft and compliant material. The generallycompliant material of which the force collector 16 is comprised forexample may be a generally compliant polymer material, a generallycompliant monomer material, or another generally compliant material suchas latex. The force collector 16 may alternatively for example becomprised of a generally noncompliant material which includes compliantmaterial therein, such as an oil. The generally compliant material andthe generally non-compliant material may comprise a generally soft lowdurometer material or a generally non-low durometer non-compliantmaterial. The system 10 may include a protective cover 52, which extendsover the force collector 16 to provide additional protection for thegenerally low durometer embodiment of the force collector 16. Theprotective cover 52 may be thin, may be comprised of polyethylene, andmay have a vent hole 54 therein, for enabling the venting of trapped airtherethrough. The protective cover 52 also enables the force collector16 to slide over the patient's skin, and prevents the force collector 16from sticking to the patient's skin, when the clinician wishes toreposition the system 10. The vent hole 54 prevents the air fromexpanding as it warms up on the patient's abdomen, which may otherwisecause a zero shift in the pressure reading. The protective cover 52 isalso able to prevent sticking of the force collector 16, which mightotherwise pull on the force collector 16 causing negative pressurereadings when the protective cover 16 is unloaded and returns to itsnatural state.

An outer section-inner section ratio comprises the ratio of the linearwidth of the force collector outer section 46 to the linear width of theforce collector inner section 48. The width of the linear width of theouter section 46 of the force collector 16 comprises the linear widestwidth thereof. The ratio for example is no greater than about three andone-half to one, and may be about two and one-half to one. Aninterface-inner section ratio comprises the ratio of the cross-sectionalarea of the width of the force collector interface 50 to thecross-sectional area of the width of the force collector outer section46. The interface-inner section ratio of the interface 50 of the forcecollector 16 to the outer section 46 of the force collector 16 issubstantially minimal. The interface-inner section ratio may comprisethe ratio of the cross-sectional area of the width of the interface 50to the cross-sectional area of the width of the inner section 48. Thecross-sectional area of the width of the force collector 16 comprisesthe cross-sectional area of the widest width thereof. The ratio forexample is no greater than about eight to one, and may be about four toone.

The coefficient of thermal expansion of the solid non-fluid outersection 46 of the force collector 16 is substantially similar to thecoefficient of thermal expansion of the solid non- fluid inner section48 of the force collector 16. If there is a difference in thecoefficient of thermal expansion between the outer section 46 and theinner section 48 of the force collector 16, a zero shift in the pressurereading may result as the system 10 warms on the patient's skin. Theaverage thickness of an outer portion 56 of the outer section 46 of theforce collector 16 is less than the average thickness of an innerportion 58 of the outer section 46 of the force collector 16, toovercome slight differences in coefficients of thermal expansion of theouter portion 56 and the inner portion 58 of the outer section 46 of theforce collector 16. The outer portion 56 of the outer section 46 isretained firmly against a nonmoving surface, thereby keeping thethickness of the outer section. 46 down in this area, and allowing theouter portion 56 of the outer section 46 to move more freely over theinner portion of the outer section 46, so as to negate at least aportion of any expansion differences.

The pressure sensor 1.2 is able to be formed such that ratios of thepressure sensor 12 relative to the force collector 16 are substantiallyminimal so as to maximize the sensitivity of the system 10. An innersection-sensing member ratio of the inner section 48 of the forcecollector 16 to the sensing member 22 of the pressure sensor 12 issubstantially minimal. The inner section-sensing member ratio comprisesthe ratio of the area of the width of the force collector inner section48 to the width of the sensing member 22. The width of the forcecollector inner section 48 and the width of the sensing member 22comprises the width in any direction thereof. The ratio for example isno greater than about three and one-half to one, and may be about twoand one half to one. Alternatively, the inner section- sensing memberratio comprises the ratio of the area of the force collector innersection 48 to the area of the sensing member 22. The ratio for exampleis no greater than about eight to one, and may be about five to one.

The securing element 18 for example comprises a belt, which is comprisedof generally elastic material. The generally elastic material may forexample comprise an elastic nylon material, or an elastic polyestermaterial. The supporting element 14 also leverages the pressure sensor12, so as to enable the securing element 18 to load the pressure sensor12 onto the abdomen, with substantially minimal retention pressureexerted by the securing element 18 on the pressure sensor 12. Further,the supporting element 14 is comprised of a flexible material or anon-flexible material, such that, in conjunction with the securingelement 18, the flexible material or the non-flexible material maintainsa load on the pressure sensor 12 during abdominal changes in response tocontractions. The flexible material of which the supporting element 14may be comprised is preferably a flexible plastic material, whichflexible plastic material may constitute for example a thermoplasticsuch as polycarbonate.

In the embodiment as seen in FIGS. 1, 3-5, and 7-8, the supportingelement 14 further includes extending portions 60 which extend from theopposed sides 62 of the supporting element 14, which extending portions60 include opposed ends 64, to which opposed ends'66 of the securingelement 18 are attachable, to provide leverage for the force collector16. The extending portions 60 include the opposed ends 64, attachmentportions 68 at the opposed ends 64 thereof, and an attachment point 70at which the attachment portions 68 enable the securing element 18 tosecure the system 10 about the abdomen. The attachment point 70 is adistance from the force collector 16 such that the extending portions 60including the attachment portions 68 thereof leverage the forcecollector 16. The leveraging provided by the extending portions 60including the attachment portions 68 is sufficiently flexible to deflectwith the tension exerted by the securing element 18 thereon, so that thesupporting element 14 conforms to the natural curvature of the abdomen.The force collector 16 includes edges 72 thereof, and a leveraging ratioof the distance from the attachment points 70 through the edges 72 ofthe force collector 16, to the width of the force collector 16, isgreater than 1.5 to 1, and may be greater than 13 to 1.

The supporting element 14 may include an inhibiting portion 74,comprising a ridge area 76, as seen in FIG. 7, or a counterbore area 78,as shown in FIG. 8, each of which comprises a detail such as a meniscus,and which is formed relative to the bonding element adhering portion 30,for inhibiting the material of which the force collector 16 is formedfrom flowing beyond the adhering portion 30, so as to prevent thematerial from affecting the sensitivity of the system. The sensitivityof the active area in the sensing member 22 is affected by the extent ofthe force collector 16 which is supported thereon which extends beyondthe width of the sensing member 22 and is outside the active areathereof. The inhibiting portion 74 reduces the relative surface tensionof the supporting element 20 therebeyond for the nipple material of theforce collector 16, so as to resist the nipple material from flowingtherebeyond. The ridge area 76 in FIG. 7, for example, may be about0.005 inches high by 0.010 inches wide.

In the embodiment shown in FIG. 9, the opposed ends 64 of the extendingportions 60 of the supporting element 14 include slots 80 and posts 82,and the securing element 18 may have buttonholes 84 therein, the opposedends 66 of the securing element 18 are able to extend through the slots80 in the opposed ends 64 of the extending portions 60 and foldthereover, and wherein each of the buttonholes 84 is able to stretchover and interlock with the post 82 to engage therewith for securing thesystem 10 about the abdomen. Alternatively, the securing element 18 mayinclude interengageable elements whereby the opposed ends of thesecuring element 18 extend through the slots 80 and fold back thereover, such that the interengageable elements interengage for securingthereof.

The FIG. 10 embodiment illustrates the cover 44 which includes a post 86on its outer surface 88, and wherein the securing element 18 may havebuttonholes 90 therein, wherein each of the buttonholes 90 is able tostretch over and interlock with the post 86 to engage therewith, forsecuring the system 10 about the abdomen. In this embodiment, thesupporting element 14 does not include extending portions 60.

The supporting element 14 is generally low profile and lightweight. Itincludes a housing 92 which includes a mounting portion 94 for mountingthe pressure sensor 12 therein, is generally semi-spherical in shape,generally in the form of a dome, and includes a recess 96 in the form ofa well therein. The pressure sensor 12 is able to project from and bemoveable in the recess 96 of the supporting element 14. The housing 92further includes a generally rectangular-shaped back portion 98 fromwhich the mounting portion 94 projects. The supporting element 14 may beis comprised of a flexible or non-flexible material, such that theflexible or non-flexible material maintains a load on the pressuresensor 12 during abdominal changes relating to contractions. Theflexible material may comprise a flexible plastic material.

While the particular sensing system as shown and disclosed in detailherein is fully capable of obtaining the objects and providing theadvantages previously stated, it is to be understood that it is merelyillustrative of the presently preferred embodiment of the invention, andthat no limitations are intended to the details of construction ordesign shown herein other than as described in the appended claims.

I claim:
 1. A system for sensing the frequency and duration of uterinecontractions of a patient during labor and estimating the relativeintensity thereof, able to sense changes in pressure in response touterine muscle tone changes relating to contractions, and to enable afetal monitor to be connected thereto for evaluation of contractions,comprising: a supporting element, including a facing side able to facean exterior abdominal wall proximate a uterine muscle of a patient andbe positionable thereagainst, and able to support a force collector, anda pressure sensor positioned adjacent to the force collector, forsupporting the force collector and the pressure sensor such that theforce collector and the pressure sensor project therefrom, and shapedsuch that the projecting force collector and adjacent pressure sensorproject into the abdominal wall to reside at least partially below thenon-compressed surface of the abdomen to sense changes in pressure inresponse to uterine muscle tone changes relating to contractions, uponpostioning the facing side of the supporting element so as to face theexterior abdominal wall proximate the uterine muscle of the patient; aforce collector, for collecting force generated in response to uterinemuscle tone changes relating to contractions, positioned on the facingside of the supporting element and shaped so as to project therefrom soas to project into the abdominal wall to reside at least partially belowthe non-compressed surface of the abdomen upon positioning the facingside of the supporting element on the exterior abdominal wall proximatethe uterine muscle of the patient; and a pressure sensor, for sensingchanges in pressure in the force collector responsive to uterine muscletone changes, positioned adjacent to the force collector.
 2. A system asin claim 1, wherein the pressure sensor includes a supporting member,and a sensing member for sensing changes in pressure responsive touterine muscle changes relating to contractions, supportable in thesupporting member so as to project into the abdominal wall to reside atleast partially below the non-compressed surface of the abdomen, andconnectable to a fetal monitor for evaluation of contractions duringlabor.
 3. A system as in claim 2, wherein the force collector is securedto the pressure sensor so as to bear against the exterior abdominal wallproximate the uterine muscle and project into the abdominal wall toreside at least partially below the non compressed surface of theabdomen able to interact with the sensing member by displacing orcompressing so as to exert pressure on the sensing member responsive touterine muscle tone change and supported in the supporting member.
 4. Asystem as in claim 3, wherein the force collector includes an outersection, an inner section, and an interface between the outer sectionand the inner section.
 5. A system as in claim 4, wherein the pressuresensor is able to be formed such that an inner section-sensing memberratio of the inner section of the force collector to the sensing memberof the pressure sensor is substantially minimal.
 6. A system as in claim4, wherein the coefficient of thermal expansion of the outer section ofthe force collector is substantially similar to the coefficient ofthermal expansion of the inner section of the force collector.
 7. Thesystem as in claim 4, wherein the force collector further includes anouter portion of the outer section, and an inner portion of the outersection, and wherein the average thickness of the outer portion of theouter section of the force collector is less than the average thicknessof the inner portion of the outer section of the force collector, so asto overcome slight differences in coefficients of thermal expansion ofthe outer portion and the inner portion of the outer section of theforce collector.
 8. A system as in claim 4, wherein an outersection-inner section ratio comprises the ratio of the linear width ofthe outer section to the linear width of the inner section.
 9. A systemas in claim 8, wherein the ratio is no greater than about three andone-half to one.
 10. A system as in claim 9, wherein the ratio is abouttwo and one-half to one.
 11. A system as in claim 1, further comprisinga securing element, for enabling the securing of the supporting elementand the pressure sensor about the exterior abdominal wall, able toretain the supporting element, the force collector, and the pressuresensor in position against the exterior abdominal wall proximate theuterine muscle.
 12. A system as in claim 1, wherein the sensing memberof the pressure sensor comprises an active element, and includesresistors able to change the resistance with changes in appliedpressure.
 13. A system as in claim 1, wherein the supporting elementincludes opposed sides, and extending portions which extend from theopposed sides, which extending portions include opposed ends, able toenable opposed ends of a securing element to be attachable thereto, toprovide leverage for the force collector.
 14. A system as in claim 13,wherein the extending portions of the supporting element further includeattachment portions at the opposed ends thereof for enabling thesecuring element to secure the system about the abdomen, and wherein theleveraging provided by the extending portions including the attachmentportions is sufficiently flexible to deflect with the tension exerted bythe securing element thereon, so that the supporting element conforms tothe natural curvature of the abdomen.
 15. A system as in claim 14,wherein the force collector includes an edge thereof, and a leveragingratio of the distance from the attachment point through the edge of theforce collector, to the width of the force collector, is greater than1.5 to
 1. 16. A system as in claim 15, wherein the leveraging ratio isgreater than 13 to
 1. 17. A system of claim 13, wherein the opposed endsof the extending portions include slots and posts, and the securingelement includes opposed ends and has buttonholes, the opposed ends ofthe securing element are able to extend through the slots in opposedends of the extending portions and fold thereover, and wherein each ofthe buttonholes is able to stretch over and interlock with the post toengage therewith for securing the system about the abdomen.
 18. A systemof claim 13, wherein the opposed ends of the extending portions includeslots, and the securing element includes opposed ends, each of whichincludes interengageable elements, the opposed ends of the securingelement are able to extend through the slots in the opposed ends of theextending portions and fold thereover, and the interengageable elementsare able to interengage for securing thereof.
 19. A system as in claim13, wherein a protective cover has a vent hole therein, for enabling theventing of trapped air therethrough.
 20. A system as in claim 13,wherein the opposed end connectors of the supporting element eachinclude a slot, and the opposed ends of the extending element arecomprised of interengageable elements, such that the opposed ends of theextending element are able to extend through the slot and fold back overso that the interengageable elements interengage.
 21. A system as inclaim 13, wherein the opposed end connectors each include a post, andthe opposed ends of the extending element have buttonholes therein, eachof which is able to stretch over the post to engage therewith.